DESCRIPTION (Investigator's Abstract): The goal of this project is to discover genes that are differentially expressed during metastasis of prostate cancer. Potentially such transcripts and their products will be useful in detection, prognosis and ultimately, understanding and treatment of the disease. Because metastasis is a transient and rare event, it is difficult to study. We will concentrate on systems that reveal stark and potentially relevant phenotypic differences among cells of differing metastatic potential in vitro or which appear to model parts of the process in vivo. We have found that cell lines from a variety of different tumor types that differ in their metastatic potential generally demonstrated (i) differential clonogenic growth potential, (ii) strikingly different survival in serum starvation experiments, and (iii) phenotypic reversal of the metastatic phenotypein vitro and in vivo aft treatment with synthetic glycoamines, which are potential anti-metastatic drugs. We have shown that prostate cancer cell lines that differ in metastatic ability are also transcriptionally distinct, monitored on cDNA array. Remarkably, when cells selected for high metastatic ability are serum-starved and treated with glycoamines most of the transcriptional changes that would otherwise occur upon serum removal do not occur. These observations suggest that we can reveal functionally relevant differences in mode1 systems of the process of metastasis. We will study gene expression in an orthotopic human prostate cancer model in nude mice. Gene expression will also be measured during efficacy experiments of the leading clinic drug candidate, the Lac-L-Leu glycosarnine analog. To model one stage of metastasis we will inject cells of differing metastatic potential into the circulation of rabbits, recover cells by magnetic cell sorting base on an epithelial surface antigen, and then monitor changes in gene expression. We will also study leukapheresis-enriched disseminated cancer cells from human volunteers with advanced disease. To determine which, if any, of the gene status changes are likely to be diagnostic, prognostic, or of potential mechanistic or therapeutic value, we will examine a selected subset of genes in fresh pathology samples and in the blood-borne human prostate cancer cells using mRNA and protein expression-based assays. A set of 20-30 of the most relevant gene will be selected from the differential gene expression list and the levels of the corresponding proteins will be evaluated in time-course S35-methionine labeling and Western blot experiments. Subsequently the expression profile of these protein products will be studied in human prostate tumor samples by immunofluorescence analysis and immunohistochemistry to better correlate gene expression changes with phenotype.